This invention relates to coupling devices for hoses and flexible irrigation conduits, particularly those having an irregular outer periphery as viewed in radial cross section.
Various types of couplings are known for conduits having a regular, i.e., a circular radial cross section and a wall of uniform thickness. Couplings are generally easy to attach and seal to conduits having such a regular configuration, provided the conduits have walls of uniform thickness. However, with conduits having an irregular configuration or nonuniform wall thickness, it becomes difficult to provide an effective seal between the coupling and the conduit.
A common type of irregularly configured conduit having a noncircular cross section comprises a flexible conduit having a large primary passage and a secondary passage with a common wall between the passages. The flexible conduit is typically extruded and has a wall thickness that varies within a certain tolerance. With such a conduit, it is difficult to provide a good seal between the conduit and the coupling because of the noncircular configuration and varying thickness of the conduit wall.
An example of a coupling device for an irrigation conduit having a generally circular cross section is shown in U.S. Pat. No. 4,021,061. This patent shows a coupling device with an inner or male member having near its end an enlarged circumferential portion with a series of conical stages with different degrees of taper. An annular female member or retaining sleeve is retained on the male member. A hose or conduit is attached to the connector by pushing it through an annular gap between the female sleeve portion and the enlarged male member. A wedging action is created by the inside sleeve surface and one conical surface of the male member to provide some degree of sealing.
The above patent also shows a connector for a conduit of irregular configuration, such as a conduit having a primary passage and a secondary passage. In this embodiment, the female sleeve member has a notch or cut out section with a radially extending bearing surface that forms a surface for providing a pinching action on the secondary passage of the dual passage conduit.
The problem with the above construction is that when the coupling is used with conduits of irregular configuration or nonuniform wall thickness, the female sleeve member does not provide an effective seal around the conduit and on the secondary passage.